Questions About Exposure Compensation
Aug 13, 2017 10:09:38 #
Mac wrote:
Is the camera's Exposure Compensation the same as adjusting exposure in post?
Is there an advantage of one over the other?
If not could you explain the difference?
Is there an advantage of one over the other?
If not could you explain the difference?
The difference is that, in camera, you can recover areas that would record at 0 or as 255 in luminance. By doubling the light(1 stop of EC), you can split those dark areas into two regions ;
0 = 0 - 0.49,
1 = 0.5 to 1.49;
double those, and
0 = 2*(0-0.245),
1 = 2*(0.25 - 0.745),
2 = 2*(0.75 - 1.249),
3 = 2*(1.25 - 1.745).
In post, if you double the pixel values, then 0=0, 1=2, 2=4 and you lose all that data in between - a 16 bit picture effectively becomes an 8 bit image. Now, designers have come up with algorithms to correct this loss of data, but it does not perform perfectly.
Similarly, the pixel will only store up to 255 steps. In camera, if you halve the exposure, you can recover values that are over 255, because 256 becomes 128, and 510 becomes 255. In post, those values above 255 are simply lost - gone! All you can do is guess at their value, and computer systems, when asked to guess, will ALWAYS return the same answer.
In Camera
127 = 0.5 * 254
128 = 0.5 * 256
200 = 0.5 * 400
250 = 0.5 * 500
255 = 0.5 * 510
but notice,
3 = 0.5 * 6
3 = 0.5 * 5
2 = 0.5 * 4
2 = 0.5 * 3
1 = 0.5 * 2
1 = 0.5 * 1
0 = 0.5 * 0
In Post:
256 - 510 (or greater) becomes 128
254 - 255 becomes 127
100 - 101 becomes 51
Aug 13, 2017 10:11:45 #
Are computers going to ultimately take the fun out of everything...even thinking ?
Aug 13, 2017 10:45:18 #
Aug 13, 2017 11:01:39 #
DJCard wrote:
Exposure compensation vs. post-production editing: to understand this excellent question better, exactly what is EC adjusting (aperture, shutter speed or ISO) when, for example, shooting RAW in Manual with auto ISO?
It is not manual if you are using auto ISO. That is still auto exposure. You are just deciding to let the camera determine the ISO instead of determining the shutter speed when you use aperture priority, or determining the aperture when you use shutter priority.
Aug 13, 2017 11:15:10 #
Gene 51, are these images both SOOC? I think I am underexposing all my photos and have to correct in LR. I'm afraid of blowing out the highlights, but it's taking more time to edit. I need to work on getting it right in the camera.
Gene51 wrote:
To a degree it is similar, but only if you shoot r... (show quote)
Aug 13, 2017 11:16:50 #
Good stuff here!!!
So, let me throw another piece into the equation. A few moths ago I started using the Color Checker Passport with my camera. I shoot RAW, but these changes are applied in PP with the CCP. How is this relating to the origional exposure and settings? It seems to me to be about getting the proper white balance and color tint or corrections. Perhaps Gene or others can shed some more light on this piece. I was originally sceptical when I first heard about the tool a few years ago. But after using it I find it is a very good tool and perhaps some of the best money I have spent on photography.
Best,
Todd Ferguson
So, let me throw another piece into the equation. A few moths ago I started using the Color Checker Passport with my camera. I shoot RAW, but these changes are applied in PP with the CCP. How is this relating to the origional exposure and settings? It seems to me to be about getting the proper white balance and color tint or corrections. Perhaps Gene or others can shed some more light on this piece. I was originally sceptical when I first heard about the tool a few years ago. But after using it I find it is a very good tool and perhaps some of the best money I have spent on photography.
Best,
Todd Ferguson
Aug 13, 2017 11:17:58 #
advocate1982 wrote:
It is not manual if you are using auto ISO. That is still auto exposure. You are just deciding to let the camera determine the ISO instead of determining the shutter speed when you use aperture priority, or determining the aperture when you use shutter priority.
I agree when the mode dial is set to "manual" with auto ISO turned on, it is not technically full manual. But, it is interesting to note, per our discussion here, exposure compensation appears to have no effect in "manual mode" unless auto ISO is turned on, in which case exposure compensation changes ISO!
Aug 13, 2017 11:22:03 #
DJCard wrote:
I agree when the mode dial is set to "manual" with auto ISO turned on, it is not technically full manual. But, it is interesting to note, per our discussion here, exposure compensation appears to have no effect in "manual mode" unless auto ISO is turned on, in which case exposure compensation changes ISO!
I think the exposure compensation not working in manual - is camera dependent. It works just fine on my D300 and D200.
Aug 13, 2017 11:25:55 #
advocate1982 wrote:
I think the exposure compensation not working in manual - is camera dependent. It works just fine on my D300 and D200.
EC appears to change exposure with my Nikon D750 in manual mode only when auto ISO turned on, in which case EC merely changes the ISO!
Aug 13, 2017 11:36:00 #
Gene51 wrote:
Yeah, that's because having "auto ISO" on turns a major component of control over to the camera. I virtually never use "auto ISO", and I have never used TAv mode on my Pentax cameras {essentially same effect}; perhaps this is "old film guy" behavior, but I want to have complete control of ISO. I appreciate automation, so I hardly ever use "M" mode, but when I do, I do it because I want to be in complete control of every aspect of exposure.Shoot raw, manual and auto ISO and attempting to u... (show quote)
Aug 13, 2017 11:45:58 #
rehess wrote:
Yeah, that's because having "auto ISO" on turns a major component of control over to the camera. I virtually never use "auto ISO", and I have never used TAv mode on my Pentax cameras {essentially same effect}; perhaps this is "old film guy" behavior, but I want to have complete control of ISO. I appreciate automation, so I hardly ever use "M" mode, but when I do, I do it because I want to be in complete control of every aspect of exposure.
I agree with you regarding manual mode. I like to control ISO. But, since the question was regarding EC vs. PP, I thought I would add "manual mode" to the discussion.
Aug 13, 2017 12:15:20 #
BebuLamar wrote:
No
You seem to be a serial contributor of "clever" useless remarks.
Why don't you look in a mirror and tell them to the only person who cares.
Aug 13, 2017 12:30:58 #
DJCard wrote:
Which is totally appropriate because I use "manual mode" as a primitive way of achieving what EC is designed to achieve.I agree with you regarding manual mode. I like to control ISO. But, since the question was regarding EC vs. PP, I thought I would add "manual mode" to the discussion.
Aug 13, 2017 12:48:50 #
Excellent explanation, Gene.
--Bob
--Bob
Gene51 wrote:
To a degree it is similar, but only if you shoot r... (show quote)
Aug 13, 2017 13:04:59 #
ricardo7 wrote:
Close. With exposure compensation you are basically fooling the meter to
over expose or under expose. You are using exposure compensation
because you are finding the lighting conditions in which you are
working consistently give you over or under exposed pictures. With
PP you can change the exposure and do the same basic thing, but you may
not be able to make as big an adjustment as you could in camera.
over expose or under expose. You are using exposure compensation
because you are finding the lighting conditions in which you are
working consistently give you over or under exposed pictures. With
PP you can change the exposure and do the same basic thing, but you may
not be able to make as big an adjustment as you could in camera.
I would reword that to say "With exposure compensation you are basically fooling the meter to
expose less or more." You do this to compensate for an improperly exposure.
Exposure compensation in PP CANNOT recover blown highlights or detail lost in shadow.
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